This application is based on and incorporates herein by reference Japanese Patent Application No. 2003-155808 filed on May 30, 2003.
1. Field of the Invention
The present invention relates to a brush holder device, which securely holds brush holders of a dynamoelectric machine.
2. Description of Related Art
A brush holder device of a dynamoelectric machine, more specifically of a motor, generally includes metal brush holders and a holder base. Each brush holder receives a corresponding brush in a manner that allows sliding movement of the brush relative to a commutator. Furthermore, the brush holders are securely installed to a front surface of the holder base.
Each brush holder is bent to have a square horseshoe shaped cross section and includes a pair of lateral walls and a top wall. The top wall extends continuously from each of the lateral walls. A securing claw is formed in a lower edge of each lateral wall and is bent. More specifically, each securing claw is inserted through a corresponding receiving through hole formed in the holder base. A distal end of the securing claw, which protrudes from a rear surface of the holder base, is bent, so that the brush holder is secured to the holder base by staking.
At this time, each securing claw is desirably bent to make close contact with the rear surface of the holder base. However, due to springback property of the metal, it is difficult to bent the distal end of the securing claw in close contact with the rear surface of the holder base. Thus, the brush holder is loosely attached to the holder base. As a result, vibration of the brush, which is induced due to sliding engagement of the brush with the rotating commutator, causes wobbling of the brush holder, thereby generating noise.
In order to address the above disadvantage, it is conceivable to increase a press load applied to each securing claw to secure the securing claw to the holder base by the staking. However, when the press load becomes large, the holder base receives the large press load and may be thereby deformed or damaged.
Japanese Unexamined Patent Publication No. 11-27906, which corresponds to U.S. Pat. No. 6,288,469, addresses the above disadvantage by providing four diagonally bent securing claws in a brush holder. The four securing claws are inserted through corresponding securing through holes, which penetrate through a holder base at four corners of the brush holder. The diagonally opposed securing claws are bent toward each other, so that a side edge of each securing claw engages a peripheral edge (an inner peripheral surface) of the corresponding receiving through hole. In this way, wobbling of the brush holder relative to the holder base is more effectively limited.
However, in this case, since the side edges of the securing claws engage the peripheral edges of the corresponding receiving through holes, the receiving through holes, which penetrate through the holder base, are required. Thus, in the case where the holder base is relatively small and is made of resin, the provision of the receiving through holes reduces strength of the holder base. Thus, at the time of staking of the securing claws, a crack may be generated in the peripheral edge of the receiving through hole. Furthermore, this technique cannot be applied to a case where the securing claws are secured to the holder base only at peripheral edges of the holder base without providing the receiving through holes for receiving the securing claws.
The above disadvantages are also true in metal terminal plate elements, which are secured to the holder base by staking in a manner similar to that of the above brush holder and are electrically connected to electrical components, such as the brush.
The present invention addresses the above disadvantages. Thus, it is an objective of the present invention to provide a brush holder device, in which at least of one of each metal brush holder and each metal terminal plate element is more effectively secured to a holder base through staking of securing claws against the holder base.
To achieve the objective of the present invention, there is provided a brush holder device for a dynamoelectric machine. The brush holder device includes a holder base, at least one brush holder and at least one brush. The holder base has axially opposed first and second sides and includes a plurality of staking projections. Each staking projection projects from a base surface of the holder base on the second side of the holder base. The at least one brush holder is made from a metal plate that is bent into a predetermined shape and is securely installed to the first side of the holder base. Each of the at least one brush holder includes a plurality of securing claws, which are secured to the holder base by staking. Each securing claw includes a retorted portion, which is retorted toward the base surface on the second side of the holder base beyond a top of a corresponding one of the plurality of staking projections. Each of the at least one brush is received in a corresponding one of the at least one brush holder in a slidable manner in a sliding direction toward and away from a commutator of the dynamoelectric machine.
To achieve the objective of the present invention, there is provided a brush holder device for a dynamoelectric machine. The brush holder device includes a holder base, at least one brush holder, at least one brush and at least one terminal element. The holder base has axially opposed first and second sides and includes at least one staking projection, which projects from a base surface of the holder base on the second side of the holder base. The at least one brush holder is made from a metal plate that is bent into a predetermined shape and is securely installed to the holder base. Each of the at least one brush is received in a corresponding one of the at least one brush holder in a slidable manner in a sliding direction toward and away from a commutator of the dynamoelectric machine. The at least one terminal plate element is made from metal and is securely installed to the first side of the holder base such that the at least one terminal plate element is electrically connected to at least one of the at least one brush. Each of the at least one terminal plate element includes at least one securing claw, which is secured to the holder base by staking. Each of the at least one securing claw of each of the at least one terminal plate element includes a retorted portion, which is retorted toward the base surface on the second side of the holder base beyond a top of a corresponding one of the at least one staking projection.